At present, band pass and low pass filters are used in a variety of electronic applications to provide needed filtering and/or processing of digital signals. One exemplary application is with Software Defined Radio (SDR) technology. Other applications involve DVD players, High Definition Television (HDTV) receivers, video games and digital music storage and playback devices, just to name a few.
In many applications, the cost of the electronic filtering subsystem(s) of the device is an important consideration in the design of the device. Furthermore, the physical size of the circuit components required to implement many existing digital filter systems does not lend itself well to the implementation of the digital filter using very large scale integration (VLSI) technology. The ability to provide various electronic circuits using VLSI technology is particularly desirable because VLSI technology enables various electronic circuits to be implemented in a highly space efficient manner. This in turn facilitates highly compact packaging of digital circuits, which is important in many applications, and particularly in applications involving hand held transceivers and other hand held digital devices.
One particular form of digital filter presently in use is the finite impulse response (FIR) filter. The conventional FIR filter is shown in FIG. 3. This filter, while effective as a band pass or low pass filter, nevertheless requires a fair number of independent hardware component parts. More specifically, the conventional FIR filter may require hundreds of multipliers and adders depending on the performance requirements of the filter (i.e., pass band, stop band, and desired pass band and stop band error performance, just to name a few).
Accordingly, at the present time there is a high level of interest in producing high speed pass band and low pass filters that are of simpler and more cost effective construction than presently available FIR filters, while still providing performance comparable to an optimally designed FIR filter. There is also a strong interest in providing pass band and low pass filters that can be implemented using VLSI technology in application specific integrated circuits (ASICs) or in Field Programmable Gate Arrays (FPGAs) to form highly space efficient digital signal filtering circuits that are well adapted for use in a wide variety of military and consumer electronic devices.